Checking the Cooling Fan Operation
CHECKING THE COOLING FAN OPERATION
For a complete wiring diagram, refer to the Wiring Information. Electrical Diagrams
Theory of Operation
The Powertrain Control Module (PCM) sends a signal to the Totally Integrated Power Module (TIPM) to turn the cooling fan on or off depending upon the engine coolant temperature. The low speed cooling fan is commanded on when the temperature is at or above 103° C (217° F) and turned off at or below 101° C (214° F). The high speed cooling fan is commanded on when the temperature is at or above 108° C (226° F) and turned off at or below 105° C (221° F).
1. RADIATOR FAN HIGH RELAY
1. Turn the ignition on.
2. With the scan tool, actuate the High Speed Rad Fan Control State.
Does The Large Cooling Fan Operate?
Yes
- Go To 2
No
- Go To 13
2. RADIATOR FAN CONTROL RELAY
NOTE: Diagnose and repair any Coolant Fan circuit or Temperature Sensor circuit DTCs before proceeding with this test.
1. With the scan tool, actuate the Low Speed Rad Fan Control State.
Do both Cooling Fans Operate?
Yes
- Test complete.
No
- Go To 3
3. (N24) RAD FAN CONTROL RELAY OUTPUT CIRCUIT
1. Turn the ignition off.
2. Disconnect the Cooling Fan harness connector.
3. Turn the ignition on.
4. Using a 12-volt test light connected to ground, check the (N24) Rad Fan Control Relay Output circuit in the Cooling Fan harness connector.
5. With the scan tool, actuate the Low Speed Rad Fan Control State.
NOTE: The test light should be illuminated and bright. Compare the brightness to that of a direct connection to the battery.
Is the test light illuminated and bright?
Yes
- Go To 7
No
- Go To 4
4. RADIATOR FAN CONTROL RELAY
1. Turn the ignition off.
2. Verify the Radiator Fan Control Relay is installed properly and the terminals are making a tight fit.
3. Remove the Radiator Fan Control Relay and substitute it with a known good Relay.
4. Turn the ignition on.
5. Using a 12-volt test light connected to ground, check the (N24) Rad Fan Control Relay Output circuit in the Cooling Fan harness connector.
6. With the scan tool, actuate the Low Speed Rad Fan Control State.
NOTE: The test light should be illuminated and bright. Compare the brightness to that of a direct connection to the battery.
Is the test light illuminated and bright?
Yes
- Replace the Radiator Fan Control Relay.
- Perform the PCM VERIFICATION TEST. PCM Verification Test.
No
- Go To 5
5. (N24) RAD FAN CONTROL RELAY OUTPUT CIRCUIT SHORTED TO GROUND
1. Turn the ignition off.
2. Disconnect the C1 TIPM harness connector.
3. Measure the resistance between ground and the (N24) Rad Fan Control Relay Output circuit in the Cooling Fan harness connector.
Is the resistance below 100k Ohms?
Yes
- Repair the (N24) Rad Fan Control Relay Output circuit for a short to ground.
- Perform the PCM VERIFICATION TEST. PCM Verification Test.
No
- Go To 6
6. (N24) RAD FAN CONTROL RELAY OUTPUT CIRCUIT OPEN OR HIGH RESISTANCE
1. Measure the resistance of the (N24) Rad Fan Control Relay Output circuit between the Cooling Fan harness connector and the C1 TIPM harness connector.
Is the resistance above 5.0 Ohms?
Yes
- Repair the (N24) Rad Fan Control Relay Output circuit for an open or high resistance.
- Perform the PCM VERIFICATION TEST. PCM Verification Test.
No
- Go To 18
7. (N210) RAD FAN HIGH/LOW CONTROL FEED
1. Turn the ignition off.
2. Connect the Cooling Fan harness connector.
3. Remove the Radiator Fan High/Low Control Relay.
4. Turn the ignition on.
5. Using a 12-volt test light connected to ground, check the (N210) Rad Fan High/Low Control Feed circuit in the Radiator Fan High/Low Control Relay harness connector.
6. With the scan tool, actuate the Low Speed Rad Fan Control State.
NOTE: The test light should be illuminated and bright. Compare the brightness to that of a direct connection to the battery.
Is the test light illuminated and bright?
Yes
- Go To 9
No
- Go To 8
8. COOLING FAN
1. Turn the ignition off.
2. Disconnect the Cooling Fan harness connector.
3. Connect a jumper wire between cavity 1 of the Cooling Fan harness connector.
4. Turn the ignition on.
5. Using a 12-volt test light connected to ground, check the (N210) Rad Fan High/Low Control Feed circuit in the Cooling Fan harness connector on the Cooling Fan side of the harness connector.
6. With the scan tool, actuate the Low Speed Rad Fan Control State.
NOTE: The test light should be illuminated and bright. Compare the brightness to that of a direct connection to the battery.
Is the test light illuminated and bright?
Yes
- Replace the Cooling Fan.
- Perform the PCM VERIFICATION TEST. PCM Verification Test.
No
- Go To 11
9. RADIATOR FAN HIGH/LOW CONTROL RELAY
1. Turn the ignition off.
2. Verify the Radiator Fan High/Low Control Relay is installed properly and the terminals are making a tight fit.
3. Remove the Radiator Fan High Low Control Relay and substitute it with a known good Relay.
4. Turn the ignition on.
5. With the scan tool, actuate the Low Speed Rad Fan Control State.
Do Both Cooling Fans Operate?
Yes
- Replace the Radiator Fan High/Low Control Relay.
- Perform the PCM VERIFICATION TEST. PCM Verification Test.
No
- Go To 10
10. RADIATOR FAN HIGH RELAY
1. Turn the ignition off.
2. Verify the Radiator Fan High Relay is installed properly and the terminals are making a tight fit.
3. Remove the Radiator Fan High Relay and substitute it with a known good Relay.
4. Turn the ignition on.
5. With the scan tool, actuate the Low Speed Rad Fan Control State.
Do Both Cooling Fans Operate?
Yes
- Replace the Radiator Fan High Relay.
- Perform the PCM VERIFICATION TEST. PCM Verification Test.
No
- Go To 18
11. (N210) RAD FAN HIGH/LOW CONTROL FEED SHORTED TO GROUND
1. Turn the ignition off.
2. Disconnect the C1 TIPM harness connector.
3. Measure the resistance between ground and the (N210) Rad Fan High/Low Relay Feed circuit in the Cooling Fan harness connector.
Is the resistance below 100 Ohms?
Yes
- Repair the (N210) Rad Fan High/Low Control Feed circuit for a short to ground.
- Perform the PCM VERIFICATION TEST. PCM Verification Test.
No
- Go To 12
12. (N210) RAD FAN HIGH/LOW CONTROL FEED OPEN OR HIGH RESISTANCE
1. Measure the resistance of the (N210) Rad Fan High/Low Control Feed circuit between the Cooling Fan harness connector and the C1 TIPM harness connector.
Is the resistance above 5.0 Ohms?
Yes
- Repair the (N210) Rad Fan High/Low Control Feed circuit for an open or high resistance.
- Perform the PCM VERIFICATION TEST. PCM Verification Test.
No
- Go To 18
13. (Z904) GROUND CIRCUIT OPEN
1. Turn the ignition off.
2. Disconnect the Cooling Fan harness connector.
3. Using a 12-volt test light connected to voltage, check the (Z904) Ground circuit in the Cooling Fan harness connector.
NOTE: The test light should be illuminated and bright. Compare the brightness to that of a direct connection to the battery.
Is the test light illuminated and bright?
Yes
- Go To 14
No
- Repair the (Z904) Ground circuit for an open or high resistance.
- Perform the PCM VERIFICATION TEST. PCM Verification Test.
14. (N23) RAD FAN HIGH RELAY OUTPUT CIRCUIT
1. Turn the ignition on.
2. Using a 12-volt test light connected to ground, check the (N23) Rad Fan High Relay Output circuit in the Cooling Fan harness connector.
3. With the scan tool, actuate the High Speed Rad Fan Control State.
NOTE: The test light should be illuminated and bright. Compare the brightness to that of a direct connection to the battery.
Is the test light illuminated and bright?
Yes
- Replace the Cooling Fan.
- Perform the PCM VERIFICATION TEST. PCM Verification Test.
No
- Go To 15
15. RADIATOR FAN HIGH RELAY
1. Turn the ignition off.
2. Verify the Radiator Fan High Relay is installed properly and the terminals are making a tight fit.
3. Remove the Radiator Fan High Relay and substitute it with a known good Relay.
4. Using a 12-volt test light connected to ground, check the (N23) Rad Fan High Relay Output circuit in the Cooling Fan harness connector.
5. With the scan tool, actuate the High Speed Rad Fan Control State.
NOTE: The test light should be illuminated and bright. Compare the brightness to that of a direct connection to the battery.
Is the test light illuminated and bright?
Yes
- Replace the Radiator Fan High Relay.
- Perform the PCM VERIFICATION TEST. PCM Verification Test.
No
- Go To 16
16. (N23) RAD FAN HIGH RELAY OUTPUT CIRCUIT SHORTED TO GROUND
1. Turn the ignition off.
2. Disconnect the C4 TIPM harness connector.
3. Measure the resistance between ground and the (N24) Rad Fan High Relay Output circuit in the Cooling Fan harness connector.
Is the resistance below 100 Ohms?
Yes
- Repair the (N23) Rad Fan High Relay Output circuit for a short to ground.
- Perform the PCM VERIFICATION TEST. PCM Verification Test.
No
- Go To 17
17. (N23) RAD FAN HIGH RELAY OUTPUT CIRCUIT OPEN OR HIGH RESISTANCE
1. Measure the resistance of the (N23) Rad Fan High Relay Output circuit between the Cooling Fan harness connector and the C4 TIPM harness connector.
Is the resistance above 5.0 Ohms?
Yes
- Repair the (N23) Rad Fan High Relay Output circuit for an open or high resistance.
- Perform the PCM VERIFICATION TEST. PCM Verification Test.
No
- Go To 18
18. TOTALLY INTEGRATED POWER MODULE (TIPM)
NOTE: Before continuing, check the TIPM harness connector terminals for corrosion, damage, or terminal push out. Repair as necessary.
1. Using the schematics as a guide, inspect the wire harness and connectors. Pay particular attention to all Power and Ground circuits.
Were there any problems found?
Yes
- Repair as necessary.
- Perform the PCM VERIFICATION TEST. PCM Verification Test.
No
- Replace the Totally Integrated Power Module (TIPM).
- Perform the BODY VERIFICATION TEST. Body Verification Test.